Filter assembly with pleated filter element

ABSTRACT

In dry copying machines utilizing particulate toner a particle conveying system including a plurality of pneumatic ducts and a blower with a vacuum-type pickup device attached to an inlet of the blower and positioned to remove loose particles from the copies as they egress from the copying machine, a centrifugal separator positioned in the pneumatic system to receive the air and particles from the vacuum pickup device and separate the particles from the bulk of the air, a particle settling chamber having baffles therein attached to the copying machine and receiving separated particles from the separator so as to return them to active use in the copying machine and further having an outlet duct attached to the blower to reduce the pressure therein slightly below atmospheric, and a filter assembly attached to the air outlet of the separator so that air leaving the separator is filtered prior to being returned to the atmosphere. The filter assembly is constructed from an extruded plastic housing having two side walls and a joining wall connected to provide a U-shaped cross section and a pleated filter element connected to the sidewalls opposite the joining wall and end walls formed of plastic while in its formable state and subsequently hardened to provide sealing engagement with the ends of said housing and pleated filter.

United States Patent Rolland [451 Oct. 3, 1972 [54] FILTER ASSEMBLY WITHPLEATED FILTER ELEMENT [73] Assignee: Donaldson Company, Inc.,Minneapolis, Minn.

[22] Filed: April 23, 1970 [21] Appl. No.: 43,304

Related US. Application Data [62] Division of Ser. No. 711,114, March 6,1968.

[52] US. Cl. ..55/499, 55/337, 55/467, 55/500, 55/521 [51] Int. Cl...B0ld 27/06 [58] Field of Search ..55/497500, 521, 55/337, 467; 210/493[56} References Cited UNITED STATES PATENTS 2,364,573 12/1944 Vokes..55/500 3,222,850 12/1965 Hart ..55/521 3,458,977 8/1969 Young et a1...55/497 3,470,680 10/1969 Avera ..55/497 3,471,023 10/ 1969 Rosaen ..21 0/493 Primary Examiner-Bemard Nozick Attorney-Merchant & Gould [s71ABSTRACT In dry copying machines utilizing particulate toner a particleconveying system including a plurality of pneumatic ducts and a blowerwith a vacuum-type pickup device attached to an inlet of the blower andpositioned to remove loose particles from the copies as they egress fromthe copying machine, a centrifugal separator positioned in the pneumaticsystem to receive the air and particles from the vacuum pickup deviceand separate the particles from the bulk of the air, a particle settlingchamber having baffles therein attached to the copying machine andreceiving separated particles from the separator so as to return them toactive use in the copying machine and further having an outlet ductattached to the blower to reduce the pressure therein slightly belowatmospheric, and a filter assembly attached to the air outlet of theseparator so that air leaving the separator is filtered prior to beingreturned to the atmosphere. The filter assembly is constructed from anextruded plastic housing having two side walls and a joining wallconnected to provide a U-shaped cross section and a pleated filterelement connected to the sidewalls opposite the joining wall and endwalls formed of plastic while in its formable state and subsequentlyhardened to,provide sealing engagement with the ends of said housing andpleated filter.

2 Claims, 6 Drawing Figures PATENTEnnm 1872 3.695.012

sum 2 OF 2 l I l l I I M -II|| U FILTER ASSEMBLY WITH PLEATED FILTERELEMENT CROSS REFERENCE TO RELATED APPLICATIONS This application is adivision of the copending application entitled Pneumatic Separator,Filter and Particle Conveying System, filed Mar. 6, 1968, Ser. No. 711,1 14, by the same applicant.

BACKGROUND OF THE INVENTION 1. Field Of The Invention In dry copyingmachines utilizing particulate toner, loose toner particles must beremoved from the surface of the copies prior to permanently fixing theparticles thereto. Also, much of the toner adheres to the copies withoutbeing permanently affixed thereto. These loose toner particles must beremoved from the copies prior to the egress of the copies from thecopying machine or they will contaminate the surrounding atmosphere, aswell as the machine and the operator. These particles, if collected, arereusage. It should be understood that the present invention can beutilized on many machines utilizing particulate matter therein andcopying machines are only utilized in the description for exemplarypurposes.

2. Description of the Prior Art In the prior art toner particles arecollected from the copies by means of a pneumatic stream and they aresubsequently removed from the pneumatic stream and stored in areceptacle. This system is undesirable because the receptacle requiresperiodic emptying and handling of the toner particles by an operator. Insome instances the toner particles are simply passed into theatmosphere. This system is undesirable because of the contamination ofthe surrounding atmosphere and the loss of the toner particles.

SUMMARY OF THE INVENTION The present invention pertains to animprovement in copying machines utilizing particulate toner including apneumatic conveyance system having a plurality of conduits operativelyattached to propellingmeans for providing pneumatic flow therein withtoner particle pickup means attached to an inlet thereof and positionedadjacent the copy outlet, separating means receiving the toner particlesfrom the pickup means and separating them from the main pneumatic flow,a particle settling chamber receiving the toner particles from theseparating means and attached to the copying machine so as to return theparticles to reuse, said settling chamber having a pneumatic outletconduit attached to an inlet of the pneumatic conveyance system forreducing the pressure therein slightly below atmospheric, and anoptional filter assembly attached to receive the pneumatic flow from theseparating means and return it to the atmosphere after removing anyremaining toner particles therein.

It is an object of the present invention to provide an improvement incopying machines utilizing particulate toner.

It is a further object of the present invention to provide apparatus forremoving loose toner particles from copies produced by a copying machineand returning said loose particles to the copying machine for reuse.

It is a further object of the present invention to provide apparatus forreturning loose toner particles to a copying machine for reuse withoutthe necessity of a human operator.

It is a further object of the present invention to provide a new andnovel filter assembly for use with the toner particle conveying system.

These and other objects of this invention will become apparent to thoseskilled in the art upon consideration of the accompanying specification,claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings, whereinlike characters indicate like parts throughout the figures:

FIG. 1 is a view in perspective of the present apparatus;

FIG. 2 is an enlarged sectional view as seen from the line 2-2 in FIG.1;

FIG. 3 is an enlarged sectional view as seen from the line 3-3 in FIG.1;

FIG. 4 is an enlarged sectional view as seen from the line 4-4 in FIG.1;

FIG. 5 is an enlarged sectional view as seen from the line 5-5 in FIG.1;

FIG. 6 is a view of the inlet of the filter assembly as seen from theline 6--6 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a pneumaticconveyance system, generally designated 10, includes a plurality ofconduits 11-17 and a propelling means, blower 18. In the presentembodiment the propelling means is the blower 18 but it should beunderstood that any means of creating a pneumatic flow in the conveyancesystem 10 could be utilized by those skilled in the art and any suchpropelling means which performs the functions of this invention comeswithin the scope thereof.

The blower 18 has an inlet 20 connected to one end of the conduit 14 andan outlet 21 connected to one end of the conduit 16. The opposite end ofthe conduit 14 is connected to the outlet end of the conduit 13, whichis a Y-type coupling conduit wherein the two branches are the inletsand, combined, are approximately the same size as the outlet. One branchof the coupling conduit 13 is connected to one end of the conduit 11 theother end of which is attached to an outlet 25 of a pickup means 26. Thepickup means 26 is a vacuum type pickup which draws large quantities ofair therein under the impetus of the blower 18 and draws any loose tonerparticles adjacent thereto into the pickup means 26 with the air. Thepickup means 26 is mounted so that copies 27 pass immediately adjacentthe mouth thereof as they egress from a toner applying area.

The copies 27 are illustrated egressing from a slot 28 in a box drawn tosimulate at least a portion of a copying machine which is hereindesignated 29. The copies 27 are illustrated entering one side of thecopying machine 29 and egressing on the opposite side with loose tonerparticles 30 thereon; In FIG. 1 the mouth or inlet end of the pickupmeans 26 is slightly wider than the width of the copies 27 so that allof the loose toner particles 30 on the copies 27 are removed therefromas the copies 27 move beneath the pickup means 26.

These loose toner particles 30 and the air entering the pickup means 26pass through the conduit 1 1, coupling conduit 13, conduit 14, blower 18and conduit 16.

The opposite end of the conduit 16 is attached to an inlet 35 of aseparator generally designated 36. In this embodiment the separator 36includes a plurality of centrifugal separator elements 37 but it shouldbe understood that many other types of separators well known to thoseskilled in the art might be utilized and all such separators whichperform the functions of this invention come within the scope thereof.The separator 36 includes a generally cylindrical hollow housing 38having the inlet 35 in communication with the central opening andextending radially outwardly. from adjacent one end thereof. An outlet39 for the'main flow of air extends axially outwardly from one end ofthe housing 38 and the other end of the housing 38 has a particle outlet40, somewhat diminished in cross sectional area, threadedly engagedthereon. The centrifugal separator elements 37 (in this embodiment thereare four elements 37) are fixedly mounted between a partition 45, whichextends across the housing 38 perpendicular to the longitudinal axisthereof between the particle outlet 40 and inlet 35, and a partition 46,which extends across the housing 38 perpendicular to the longitudinalaxis thereof between the outlet 39 and the inlet 35. The partitions 45and 46 may be mounted within the housing 38 in any convenient manner andwill not be described in detail, since it does not form a part of thisinvention. Each of the centrifugal separator elements 37 includes anouter hollow cylindrical member 47 one end of which tapers radiallyinwardly toward a scavenging flow outlet 48. A second inner tubularmember 49 is mounted coaxially within the outer member 47 at the endopposite the scavenging flow outlet 48. The inner tubular member 49 hasan outer diameter substantially smaller than the inner diameter of theouter member 47 so as to form an annular inlet 50 therebetween. Theinner tubular member 49 is mounted within the outer member 47 by meansof a plurality of helical shaped fins 51 which cause air entering theannular inlet 50 to spiral toward the scavenging flow outlet 48. Becausethe outlet 48 is tapered inwardly the spiralling air reverses itslongitudinal direction and egresses through the inner tubular member 49.However, toner particles entrained in the spiralling air are forcedoutwardly by centrifugal force and egress from the centrifugal separatorelements 37 through the scavenging flow outlet 48 with a relativelysmall quantity of air utilized for the conveyance thereof. The innertubular members 49 extend through the partition 46 and the tapered endsof the outer members 47 extend through the partition 45. Thus, themajority of the air entering the inlet 35 egresses through the outlet 39while the toner particles and a small amount of conveying air egressthrough the particle outlet 40.

One end of the conduit is attached to the particle outlet 40 while theother end is attached to an inlet 55 of a particle settling chamber 56.The particle settling chamber 56, in this embodiment, forms an integralpart of the copying machine 29. However, it should be understood that inmany instances the copying machine 29 will be separate and will notconstitute a portion of this invention while the particle settlingchamber 56 is a portion of this invention and may be attached to thecopying machine 29 subsequent to the manufacture thereof. The particlesettling chamber 56 is positioned so as to be in communication with thearea in the copying machine 29 in which the toner particles 30 areapplied to the copies 27. Thus, particles returned to the particlesettling chamber 56 through the conduit 15 settle back into the copyingmachine 29 and are reused. In the present embodiment, a single baffle 57is illustrated within the particle settling chamber 56 to slow thescavenging flow of air from the particle outlet 40 of the separator 36.As the scavenging flow of air is reduced in velocity, the tonerparticles settle due to the force of gravity and enter the copyingmachine 29. It should be understood that means other than the bafile 57might be utilized, such as a plurality of baffles, additionalcentrifugal separators, etc. and all such embodiments which perform thefunctions of this invention come within the scope thereof. The particlesettling chamber 56 is provided with a pneumatic outlet 58 having oneend of the conduit 12 attached thereto. The other end of the conduit 12is attached to one branch of the Y-shaped coupling conduit 13 so as toprovide a slight suction in the particle settling chamber 56 and lowerthe pressure therein slightly below atmospheric. The pressure within theparticle settling chamber 56 is lowered slightly below atmospheric sothat particles are not forced outwardly through cracks and holes whichmay be present in the cavity. Thus, there is less chance ofcontaminating the atmosphere with escaping toner particles.

Thus, a substantial flow of air enters the pickup means 26 in a fashionto entrain loose toner particles 30 therein. The flow of air and tonerparticles passes through the separator 36 with the toner particlespassing to the particles settling chamber 56 in a scavenging flow andthe main flow of air egressing through the outlet 39 of the separator36. In some instances the separator 36 may not remove a sufficientamount of the toner particles from the main flow of air and additionalfiltering means may be desirable. To this end, the conduit 17 isattached between the outlet 39 of the separator 36 and an inlet 60 of afilter assembly generally designated 61. The filter assembly 61 includesa housing 62 having two opposed sidewalls 63 and 64 integrally joined bya third wall 65 to provide a housing 62 with a generally U-shaped crosssection. The third or joining wall 65 has an opening therethroughforming the inlet 60. In this embodiment the inlet 60 further includes ashort section of conduit 66 removably engaged in the inlet 60 by someconvenient means, such as the bayonet-type connection 67, illustrated indetail in FIGS. 4 and 6. It should be understood that the inlet 60 mightbe formed in any convenient embodiment adapted to mate with theparticular conveyance system being utilized and the conduit 66 andbayonet-type connection 67 are illustrated only for exemplary purposes.

The outermost edges of the sidewalls 63 and 64 are turned inwardly andgenerally rearwardly toward the wall 65 to form first clips 70 and 71,respectively. Second clips 72 and 73 are attached to the inner surfacesof the sidewalls 63 and 64, respectively, and extend longitudinally thelength thereof. The second clips 72 and 73 project inwardly from theinner surface of the sidewalls 63 and 64 and forwardly generallyparallel with the sidewalls 63 and 64 toward the first clips 70 and 71.In the present embodiment, the first clips 70 and 71 and second clips 72and 73 are formed as an integral part of the housing 62 in someconvenient means, such as extruding, molding, or the like. In general,if the second clips 72 and 73 are formed as an integral part of thehousing 62, the extended ends thereof must be spaced from the innersurface of the sidewalls 63 and 64 because of forming requirements.However, preferably, the housing 62 and the clips 72 and 73 will beformed from some material which is subsequently bendable so that theclips 72 and 73 can be bent into a position wherein they abut, orapproximately abut, the inner surfaces of the sidewalls 63 and 64adjacent the extended ends thereof.

A gas permeable pleated filter element 75 is positioned within thehousing 62 so that a full pleat adjacent one end thereof is engagedbetween first clip 70 and second clip 72 and a first pleat adjacent theother end thereof is engaged between first clip 71 and second clip 73.Second clips 72 and 73 are spaced from first clip 70 and 71 a distanceof approximately equal to the pleat width of the filter element 75 sothat the full pleat at either end of the element 75 may be slidlongitudinally between the cooperating clips 70-72 and 71-73 to engagethe filter element 75 fixedly within the housing 62. Further, becausethe second clips 72 and 73 are bent inwardly toward the surfaces of thesidewalls 63 and 64, the second clips 72 and 73 serve to hold the filterelement 75 fixedly within the housing 62 during further assemblyoperations. Further, sufiicient pressure on the outer pleat of thefilter element 75 by the second clip 72 and 73 may provide a sufficientseal between the filter element 75 and the housing 62 so that no furthersealant is needed therebetween.

Two end walls 80 and 81 are provided to seal the entire filter assembly61 so that all air entering the inlet 60 must pass through the filterelement 75 to egress from the filter assembly 61. In the presentembodiment, the end walls 80 and 81 are formed by some convenient meanssuch as molding, dipping, or the like and the material from which theyare formed is preferably some material easily modified to a liquid stateand relatively quickly hardenable, such as plastics and the like. Sincethe end walls 80 and 81 are preferably formed from material in theliquid state, the material adheres to and completely seals with the endsof the housing 62 and the ends of the filter element 75. Thus, thefilter assembly 61 is produced with a minimum number of operations andis very simple and efficient. It should be understood that the filterassembly 61 is not necessary to the operation of the previouslydescribed improvement in copying machines and that it is an optionalattachment which will further improve the operation thereof.

While we have shown and described a specific embodiment of thisinvention, further modifications and improvements will occur to thisskilled in the art. We desire it to be understood, therefore, that thisinvention is not limited to the particular form shown and we intend inthe appended claims to cover all modifications which do not depart fromthe spirit and scope of this invention.

What is claimed is:

1.Afilter assembl comprising: a. an elongated ousmg having two opposedside walls with inner surfaces and a wall joining said side walls, saidhousing having a generally U- shaped cross section;

b. an aperture through said joining wall forming a gas flow passage forsaid filter assembly;

0. a pleated filter element of gas permeable filter material extendingbetween said two opposed side walls, having a full pleat at each endthereof positioned against said inner surface of the adjoining sidewall;

(1. said housing having clips affixed thereto, said clips havingextended ends spaced from said inner surfaces of said side walls toreceive there-between in securing engagement said full pleats; and

e. end walls affixed to said housing and said pleated filter element andsealing the ends of said housing and pleated filter element against thepassage of gas therethrough so that all gas passing through said filterassembly passes through said pleated filter element.

2. A filter assembly as set forth in claim 1 wherein the end wallsinclude plastic material formed into walls sealingly engaged withopposite ends of said housing and said pleated filter element while in aformable state and subsequently hardened to maintain said end wallsfixedly and sealingly engaged with said housing and said pleated filterelement.

1. A filter assembly comprising: a. an elongated housing having twoopposed side walls with inner surfaces and a wall joining said sidewalls, said housing having a generally U-shaped cross section; b. anaperture through said joining wall forming a gas flow passage for saidfilter assembly; c. a pleated filter element of gas permeable filtermaterial extending between said two opposed side walls, having a fullpleat at each end thereof positioned against said inner surface of theadjoining side wall; d. said housing having clips affixed thereto, saidclips having extended ends spaced from said inner surfaces of said sidewalls to receive there-between in securing engagement said full pleats;and e. end walls affixed to said housing and said pleated filter elementand sealing the ends of said housing and pleated filter element againstthe passage of gas therethrough so that all gas passing through saidfilter assembly passes through said pleated filter element.
 2. A filterassembly as set forth in claim 1 wherein the end walls include plasticmaterial formed into walls sealingly engaged with opposite ends of saidhousing and said pleated filter element while in a formable state andsubsequently hardened to maintain said end walls fixedly and sealinglyengaged with said housing and said pleated filter element.